CRM197对豚鼠血脑屏障通透性的影响

Effect of CRM197 on the Permeability of Blood-Brain Barrier in Guinea Pigs

目的研究白喉毒素的无毒突变体CRM197对豚鼠血脑屏障通透性的影响和作用机制。方法给予豚鼠不同浓度的CRM197后,采用伊文氏兰法检测血脑屏障通透性的变化;荧光显微镜观察给予示踪剂伊文氏兰和荧光素钠后血脑屏障完整性的改变;透射电镜观察血脑屏障中血管内皮细胞间紧密连接等结构的变化。结果随着给予CRM197浓度的增加,血脑屏障对伊文氏兰的通透性逐渐增大,其中100,300,500μg/kgCRM197剂量组血脑屏障的通透性显著高于对照组(P<0.01)。给予300μg/kgCRM197后30min,未见有伊文氏兰-白蛋白渗漏到脑血管外周。透射电镜观察,不同浓度的CRM197作用后30min血脑屏障的完整性无明显改变,随着CRM197浓度的增大,脑微血管内皮细胞中吞饮小泡的数量有一定程度的增加,未见紧密连接明显开放。结论CRM197以剂量依赖的方式增加血脑屏障的通透性,其机制主要与胞吞转运增加有关,血脑屏障的完整性不受影响。

Objective To investigate the effect and mechanism of cross-reacting material 197 （CRM197） on the permeability of blood-brain barrier （BBB） in guinea pigs. Methods After injecting the different concentrations of CRM 197, the changes of BBB permeability were measured by Evans blue （EB） assay and the integrity of BBB was observed by fluorescent microscope with the infusion of the tracers of EB and sodium fluorescein （NF）. Transmission electron microscope （TEM） was used to observe the morphous of interendothelial tight junction of capillaries in BBB. Results With the increase of the concentrations of CRM197, the permeability of EB extravasation in BBB increased gradually. Compared with control group, the permeability of BBB increased significantly after treatment with CRM197 of 100, 300, 500 μg/kg （P〈0.01） 30 rain after the treatment of 300 μg/kg CRM197, no leakage of EB-albumin was found around perivascular area. The BBB remained integrated with different concentrations of CRM197 for 30 min under TEM,. With the increase of the concentrations of CRM197, the number of pinocytotic vesicles also rose to a higher level, however, no significant opening of tight junction was observed. Conclusion CRM 197 could increase the permeability of BBB in a dose-dependent manner and the increase of pinocytotic vesicles in microvessel endothelial cells might be the main mechanism, with the intergrity of BBB.